Abstract

A rapid, simple, reliable and automatic method was proposed for on-line determination of tannic acid in leather wastewaters. Based on the tannic acid reduction of phosphotungstic acid to form a blue compound in pH12.38 alkaline solutions, the shade of the blue compound is in a linear relation to the content of tannic acid at the maximum absorption peak of 700nm. The optimal experimental conditions have been obtained. The linear range of the proposed method was between 200μg L-1 to 50mg L-1. The relative standard deviation was 3.21% and 2.06% for 500μg L-1 and 20mg L-1 of tannic acid standard solution respectively (n = 10). The method had been successfully applied to determination of tannic acid in leather wastewater samples and the analytical results were satisfactory.